High maltose syrups

ABSTRACT

Storage stable high maltose starch conversion syrups having a minimum F.E. of 85%, a minimum D.E. value (dextrose equivalent) of about 50%, a maltose content of about 60 to 80% and a maltotriose content of 15 to 35%, and method for producing said syrups wherein a starch paste containing at least 5% by weight solids is saccharified with a maltogenic enzyme and amylo-1,6glucosidase.

United States Patent [1 1 Hurst et a1.

[ Feb. 12, 1974 HIGH MALTOSE SYRUPS [75] Inventors: Thomas L. Hurst;Almerin W.

Turner, both of Decatur, Ill.

[73] Assignee: A. E. Staley Manufacturing Company, Decatur, Ill.

22 Filed: May 12, 1969 [21] Appl. No.: 823,937

[52] US. Cl. 127/32, 195/31 R [51] Int. Cl Cl2d 13/02 [58] Field ofSearch..... 99/141, 142; 127/30; 195/2,

[56] References Cited UNITED STATES PATENTS 6/1959 Langlois 99/1423,137,639 6/1964 Hurst 99/142 3,535,123 10/1970 Heady 99/142 FOREIGNPATENTS OR APPLICATIONS Great Britain OTHER PUBLICATIONS Lee et al.,Archives of Biochemistry and Biophysics, Volume 116, pages 162467, 1966.

Kjolberg et al., Journal of Biochemistry, Volume 86, pages 258-262,1963.

Primary ExaminerLionel M. Shapiro Attorney, Agent, or FirmCharles J.Meyerson [5 7 ABSTRACT 8 Claims, No Drawings HIGH MALTOSE SYRUPSDISCLOSURE OF THE INVENTION This invention relates to storage stablehigh maltose starch conversion syrups having a high F .E. (fermentableextract) value and. method for producing said syrups with a maltogenicenzyme and amylo-,l,6- glucosi'dase. More particularly, this inventionis directed to storage stable high maltose starch conversion syrupshaving a minimum F.E. of 85%, a minimum D.E. value (dextrose equivalent)of about 50%, a maltose content of about 60 to 80% and a maltotriosecontent of to.35%, and method for producing said syrups wherein a starchpaste containing at least 5% by weight solids is saccharified with amaltogenic enzyme and amylo-l ,o-glucosidase.

The broad technology for producing syrups from starch, often referred toas starch conversion syrups, is well known. The starch conversion syrupsof particular commercial importance are the com syrups or syrupsproduced from corn starch. More recently, there has been a demand forspecialty type starch conversion syrups particularly those having a highF .E. In general, the F .E. or fermentable saccharides of a starch isthe total concentration of dextrose/maltose and maltotriose in thestarch conversion syrup. The high F .E. syrups are well suited asbrewing adjuncts in the manufacture of beer and inthe so-called brewprocess of making bread in commercial bakeries since they contain a highconcentration of fermentable saccharides. Of course, these syrups mustremain clear and fluid under normal storage'conditions.

As is well known, industrial starch conversion syrups are customarilysold at about 75% solids or above in order to prevent bacteriologicalspoilage during shipping and storage. This superimposes certainrestrictions on these syrups. To prevent crystallization or setting up,it is necessary to carefully regulate the dextrose and/or maltosecontents of these syrups or use heated containers for shipping andstorage with attendant higher costs. For example, high F.E. starchconversion syrups containing over 47% D.S.B. (dry solids basis) dextrosehave a decided tendency to crystallize. Under adverse storageconditions, such as is experienced during the fall and winter months,crystallization has been detected at dextrose concentrations between 41and 45% D.S.B. On the other hand, maltose has a decidedly smallertendency to crystallize than dextrose.

There has also been a demand for high RE. starch conversion syrupshaving relatively low levels of dextrose (less than 10% by weight) sincethese syrups are well suited for use in manufacture of hard candieswhere they are less susceptible to browning than ordinary corn syrupsand wherein they permit somewhat higher pH levels to be used duringboiling with sucrose without the development of excessive sucrose color.These high F .E. syrups containing a relatively low concentration ofdextrose and products produced therefrom are markedly less hygroscopicthan regular corn syrup and products produced therefrom. This propertyis'particularly beneficial in retarding crystallization of hard candiesduring shelf storage.

Prior to this invention, syrups having a high maltose content have beenprepared by the saccharification of starch or starch hydrolyzates withmaltogenic enzymes. For example, unmodified corn starch has beensaccharified with malt to produce syrups having a D.E. of about 42 to48, a F .E. of about to and a maltose content of about 50% by weight ofthe saccharified solids. Syrups having a D.E. of about 50 to 55 and aF.E. of about 75 to have been produced by saccharifying a partiallyhydrolyzed starch syrup with various amylases, as explained in BritishSpecification No. 1,037,254. These syrups, generally speaking, have arelatively high concentration of saccharides having a DP. of 4 or more(in excess of about 20% by weight), which results in the syrups having aPE. dnder about 80. Syrups having a D.E. of more than 55 and a F .E. of80 or more have been produced by further saccharifying the previouslydescribed hydrolyzates with amylol,4-glucosidase preparations, free oftransglucosidase. This type of saccharification results in the formationof large concentrations of dextrose and, in general, the maltoseconcentration of the syrup decreases as the dextrose concentrationincreases.

Recently, a process has been described wherein an aqueous 0.5% by weightstarch composition has been saccharified with a mixture of beta amylaseand amylol,6-glucosidase to produce products having substantially to 99%by weight maltose. While it is economically impractical to producestarch conversion syrups at these low solids, this process is unsuitablefor the production of storage stable commercial high F.E. syrups, sincethese syrups tend to crystallize when concentrated to solids contentnecessary to prevent bacteriological spoilage during shipping andstorage. It would appear that this process would be suitable for theproduction of crystalline maltose.

The object of this invention is to provide storage stable high maltosestarch conversion syrups having a minimum RE. of 85%, a minimum D.E.value of about 50%, a maltose content of 60 to 80% and a maltotriosecontent of 15 to 35%. Other objects will appear hereinafter.

We have now found that storage stable high maltose starch conversionsyrups containing from about 75 to 85% by weight solids having a minimumF .E. of 85%, a minimum D.E. of about 50, a maltose content of 60 to 80%by weight and a maltotriose content of 15 to 35% by weight can beprepared by saccharifying a starch paste containing from about 5 to 55%by weight solids with a maltogenic enzyme, such as beta amylase, andamylo-l ,6-glucosidase. The syrups produced in this manner generallycontain in the range of about 65 to 80% maltose, about 18 to 33%maltotriose with relatively small concentrations (usually less than 2%by weight) of dextrose and saccharides having a DR of 4 or more. Due tothe relatively high level of maltotriose, these high F .E. syrups do notcrystallize when concentrated to high solids, and accordingly, are notsubject to bacteriological spoilage during shipping or storage.

Briefly, the products of this invention are prepared by forming anaqueous starch slurry of about 5 to 55% solids. The starch slurry isthen pasted and/or thinned to a D.E. up to about 35 by the use of anacid or enzyme or a combination thereof. The resultant starch paste isthen adjusted, if necessary,'to a pH between 4.0 and 6.5, preferably toa pH between 4.5 and 5.9, and a solids content of between 5 to 55% byweight, and saccharified by adding a maltogenic enzyme and'amylo-l,6-glucosidase. The composition is maintained I at a temperatureof about 85F. to F. for from 24 to 100 hours or for a time sufficient toobtain the desired syrup. The syrup is then preferably refined andconcentrated.

The starch used in this invention may be any native starch, a modifiedstarch, or a low D.S. (degree of substitution) starch derivative. Cornstarch, tapioca starch,

rice starch, waxy maize starch, potato starch, wheat starch, sorghumstarch and waxy milo starch are representative of the starches that canbe used in this invention.

The maltogenic enzyme may be derived from a variety of sources, forexample, plants, animals or microorganisms, and may be either crude orrefined. A convenient source of maltogenic enzyme, and particularly onehaving a high concentration of beta-amylase, is barley malt. Barley maltis available from a number of commercial sources under variousproprietary names,

' The amylo-1,6-glucosidase, often referred to as pullulanase is anenzyme capable of selectively hydrolyzing alpha-l ,6-glucosidic bonds ofthe amylopectin fraction of starch. Other enzymes capable of hydrolyzingalpha-1 ,6-glucosidic bonds are referred to in the literature asiso-amylase and R-enzyme.

The preparation of an enzyme exhibiting amylo-l,6- glucosidase activitywas reported by Bender & Wallenfels in Biochemische Zeitschrift, Vol.334, pages 79-95 (1961 Other information covering the use and productionof this enzyme can be found in Methods of Enzymology, Vol. 8, pages555-559 (1966). According to the above references, amylo-l,6-glucosidase can be readily obtained from the organism Aerobacteraerogenes. Certain strains of the organism, Aerobacter aerogen es, havebeen reported to be particularly good sources for obtaining this enzyme.For example, Aerobacter aerogenes (U-58), which is reported to be adirect descendant of the original strain isolated by Bender & Wallenfelshas been found to be a particularly good source of this enzyme. Variousultraviolet induced mutants of Aerobacter aerogenes (U-58) can also beused. Other reported strains of Aerobacter aerogenes which can be usedinclude Aerobacter aerogenes ATCC 9621 and ATCC 15050.

Preparations of amylo-l ,6-glucosidase or pullulanase can be obtainedfrom the organism Aerobacter aerogenes by known cultivating methods. Asuitable technique is described in the Bender & Wallenfels publicationpreviously referred to. If desired, the crude preparation can bepurified prior to use. However, the utility of the enzyme in the processof this invention is not restricted to preparations of any specificpurity. Obviously, though, the use of an enzyme substantially free ofcontaminants would be advantageous.

The amount of amylo-l,6-glucosidase is not particularly critical anddepends to a large degree on the concentration of starch, the activityof the enzyme, reaction conditions, etc. Generally, from about 0.05 to 2units of amylo-1,6-glucosidase per gram of starch, and preferably fromabout 0.25 to 1 unit per gram of starch, are used. One unit ofamylo-1,6-g1ucosidase is defined as that amount of enzyme present in 1.0ml. of solution which, with excess pullulan as a substrate understandard conditions of assay, raises the reducing value within one hourat 45 to a value which is equivalent to 1 mg. of maltose.

In somewhat greater detail, the products of this invention are preparedby forming an aqueous starch slurry of. about 5 to 55% solids. Thestarch is then pasted and/or thinned to a D.E. up to about 35 by the useof acid or enzyme or combination thereof. Other things being equal,unthinne'd, pasted, starch substrates yield syrups having a PE. about 2%higher than thinned substrates. However, from a purely operational pointof view, it is preferred to thin the starch substrate to a D.E. of about15 to 25 using an alpha amylase, preferably that heat stable alphaamylase derived from Bacillus subtilis at 60 to C. The resultant starchpaste is then adjusted, if necessary, to a pH between 4.0

and 6.5, preferably to a pH between 4.5 and 5.9, and a solids contentbetween 5 to 55% by weight and saccharified by adding a maltogenicenzyme preparation and amy1o-1,6-glucosidase. The maltogenic enzymepreparation and amylo-1,6-g1ucosidase can be added simultaneously orsequentially with best results being obtained by adding both atsubstantially the same time. The composition is incubated at atemperature of about 85F. to F. for from 24 to 100 hours or a timesufficient to obtain a conversion product having a D.E. of at least 50%,a maltose content of 60 to 80%, a maltotriose content of 15 to 35% andyeast fermentable content of at least 85%. The syrup is then preferablyrefined and concentrated to about 75 to 85% solids.

The examples following are merely illustrative and should not beconstrued as limiting the scope of the invention.

EXAMPLE 1 Nine hundred grams of unmodified corn starch (dry solidsbasis) was slurried in 6 liters of water, adjusted to pH 5.0 and cookedin a jet cooker of the type de-.

scribed in U. S. Patent 3,101,284 at 56 psig for 15 minutes. The cookedstarch was cooled to'50C. and 1.2 grams of Wallersteins malt amylase PF(free of alpha amylase) and 2 units of amylo-l ,6-glucosidase per gramof starch was added. After saccharification for 48 hours at 50C., thesyrup had a D.E. of 57.6. After 112 hours, the starch syrup had a D.E.of 57.7, a D. 1.3, 70% maltose and about 29% maltotriose.

' EXAMPLE 2 A 35% by weight aqueous corn starch slurry was adjusted topH 8.1 and cooked in a jet cooker of the type described in U. S. Pat.No. 3,101,284 at 66 psig for 5 minutes. The cooked paste was ejectedinto a solution of alpha amylase (Bacillus subtilis) containing 2.5 SKBunits of amylase per gram of starch and maintained at F. for 2 hours.The alpha amylase was inactivated by heating at 205F. for 20 minutesforming a 15.7 D.E. starch paste. After the starch paste was cooled toroom temperature and adjusted to pH 5.7, an aqueous extract ofdistillers malt equivalent to 1.5% malt based on the starch dry solidsand 2 units of amylo-l,6- glucosidase per gram of starch was added. Thestarch V maltotriose content of about 18% to 35%.

paste was diluted into aliquots of 5.67% solids, 10.94% solids, 16%solids, 20.65% solids, 25.06% solids and 31.44% solids. After dilution,the hydrolyzates were incubated at 130 F. for 68 hours, steamed andfiltered.

mama; by weight of dextrose and saccharides having a DP. of 4 or more.

5. The conversion syrup according to claim 2 wherein the storage stablesyrup contains from 18% to The properties of the saccharified starchsyrups are set 5 33% l t i d 65% to 80% malto e.

forth below in Table l.

6. A process for forming a storage stable high maltose Table l SolidsD.E. Dextrose Maltose Maltotriose F.E.

5.67% 57.7% Trace 75.83% 21.74% 97.57% 10.94% 57.5% Trace 76.92% 21.25%98.17% 16.00% 56.5% Trace 79.16% 19.52% 98.68% 20.65% 56.9% 1.14% 77.53%19.22% 97.89% 25.06% 56.8% 1.75% 73.60% 21.80% 97.15% 31.44% 55.1% 1.95%73.16% 20.70% 95.81%

The above syru s did not crystallize on concentration to 80' solids.

'S'inc' "man'yambaaiheais sitar rammes mafia made and since many changesmay be made in the em- 7 bodiments described, the foregoing isinterpreted as illustrative only and the invention is defined by theclaims appended hereafter.

What is claimed is: l

2. The 'c'dmps ifiaizrclaina i whereinsaid syrup starch conversion syrupcomprising (a) saccharifying a starch paste containing from about 5% to55% by weight starch solids in the presence of amylo-1,6- glucosidaseand a beta-amylase preparation substantially free from alpha amylase,said saccharifying being conducted under conditions and for a period oftime suflicient to provide a conversion syrup having a minimum F.E. ofabout 95%, a minimum DB. of about 50%, a maltotriose content of about18% to a maltose content of 60% to 80%, and a maximum dextrose contentof less than 2.0%, and (b) concentrating contains from about to 85% byweigh} dry Solid} 3 the conversion syrup to about 75% to 85% by weight3. The cohversionsyrdp according to EH51; wherein the syrup ischaracterized as having a dextrose content of less than 2.0% and aminimum F .E. of about 95%.

4. The conversion syrup according to claim 1 wherein the syrup ischaracterized as having a maltotriose content from about 18% to 33% andcontains less alpha amylase comprising a heat stable enzyme of Bacillussubtilis.

2. The composition of claim 1 wherein said syrup contains from about 75%to 85% by weight dry solids.
 3. The conversion syrup according to claim1, wherein the syrup is characterized as having a dextrose content ofless than 2.0% and a minimum F.E. of about 95%.
 4. The conversion syrupaccording to claim 1 wherein the syrup is characterized as having amaltotriose content from about 18% to 33% and contains less than 2% byweight of dextrose and saccharides having a D.P. of 4 or more.
 5. Theconversion syrup according to claim 2 wherein the storage stable syrupcontains from 18% to 33% maltotriose and 65% to 80% maltose.
 6. Aprocess for forming a storage stable high maltose starch conversionsyrup comprising (a) saccharifying a starch paste containing from about5% to 55% by weight starch solids in the presence ofamylo-1,6-glucosidase and a beta-amylase preparation substantially freefrom alpha amylase, said saccharifying being conducted under conditionsand for a period of time sufficient to provide a conversion syrup havinga minimum F.E. of about 95%, a minimum D.E. of about 50%, a maltotriosecontent of about 18% to 35%, a maltose content of 60% to 80%, and amaximum dextrose content of less than 2.0%, and (b) concentrating theconversion syrup to about 75% to 85% by weight dry solids and therebyprovide a high solids, storage stable high maltose starch conversionsyrup product.
 7. The process of claim 6 wherein the starch isunthinned.
 8. The process according to claim 6 wherein the starch isthinned with a heat stable alpha amylase, said alpha amylase comprisinga heat stable enzyme of Bacillus subtilis.